How can I model a snug mesh around a complex object?
Edit: So as Batfinger says I missed the coat thing, so it should probably be done with hair particles on a cloth, I'll try to rework my answer.
The first thing that comes to mind is to use a Particle System &gt; Hair, with a leaf as object. Here is what it could give, with the Particle System settings: In Render, choose Render As &gt; Object, and for Instance Object &gt; choose the leaf object.
Give your leaf the same material as the tank hull, on the bottom of the Texture Coordinate node, don't forget to choose Object &gt; Tank so that the leaves will take the color of the area where they are emitted.